Characterization of the Optical and Gas Sensitivities of a Nickel-Doped Lithium Iron Phosphate Thin Film

The influence of heat-treatment temperature on the optical properties (refractive index, transmittance, and attenuation) and gas sensitivities of nickel-doped lithium iron phosphate (LiFe0.99Ni0.01PO4) thin films were discussed. LiFe0.99Ni0.01PO4 was synthesized in one step using hydrothermal methods and fixed to tin-diffused glass as a sensing film by spin-coating before calcination at different temperatures. The obtained thin films were characterized by refractive index, thickness, attenuation, and porosity, as well as gas sensing performances for benzene, toluene, and xylene. The experimental results indicated that the LiFe0.99Ni0.01PO4 thin films dried at 450 degrees C displayed higher refractive indices, good transparency, and less attenuation; thus, the resulting sensor of a LiFe0.99Ni0.01PO4 thin film/tin-diffused optical wave-guide exhibited a greater response to xylene in the concentration range of 0.1-1000ppm.